firmware retraction for E3D Hemera + Volcano

Notepad

@bernardomattiucci As Jay has said you would want to remove the checkbox in your slicer.

For reference (as the firmware retraction values are quite low) the Hemera retraction speeds should be between 40-70mm/s and a 0.8-1.2mm distance.
The faster your printers travel moves, the less retraction distance you need as there is less opportunity for the material to ooze

bernardomattiucci

@Notepad
Yesterday I set the following values and ran some tests that went very well.

M207
Tool 0 retract/reprime: length 1.00/1.00mm, speed 40.0/40.0mm/sec, Z hop 0.00mm

The problem occurs when the print lasts longer than 1 hour...at which point the filament tends to get stuck.

At this point the possibilities are 2:

I need to adjust the extruder screw properly.
I need to change some value in the retraction.

bernardomattiucci

@bernardomattiucci

My last setting. I'll try it tomorrow.

M207
Tool 0 retract/reprime: length 1.00/1.00mm, speed 55.0/60.0mm/sec, Z hop 0.10mm

Notepad

@bernardomattiucci

Interesting that you are saying your filament gets stuck. What type of filament are you using. I find Matte and Silk materials tend to be the most likely to clog over time.
Would it be also possible for you to show your Config.g so I can see what motor current you have your hemera set to? It could be the amperage is too high and its heating up the motor enough to soften the filament in the cold side.

tas

@Notepad

I had a Hemera + Volcano and used 0.6mm of retraction. 1.0 mm is not a lot and I don't think it would cause issues. Maybe heat is creeping up from the Super Volcano over time. If that is the case you need to improve cooling.

bernardomattiucci

@tas

I am just now doing my second print test, with a second filament that was giving me continuous problems.

The problems I was experiencing were “blockages” in the extrusion, not dependent on excessive temperature, but on failure to extrude. That is, the filament could not get out and as the extruder kept pushing, the filament was being “eroded” at the extruder drive wheel. Why does this happen?
Maybe because the settings were wrong. I had gotten a very good result with a very good PLA filament, which is now finished, and the same settings did not apply to these other filaments. And it was driving me crazy, because if I paused the printer and manually extruded some filament, it was extruded without any problem, except for the “mechanical” thinning generated by the failed extrusion.

M207
Tool 0 retract/reprime: length 0.60/0.60mm, speed 55.0/60.0mm/sec, Z hop 0.10mm

So?
Reading the last comment, this morning I set the firmware retraction to 0.6mm and everything seems to be fine.

As a result... with 1mm, the extruder retracted the filament, but failed to send it completely back into place within the set time. And that, in the long run, created a problem that resulted in filament blockage--due essentially to the overlap, I think, of 2 extrusion commands. Or something like that.

tas

@bernardomattiucci
It is surprising that 1mm of retraction is too much. At least it is working now.

bernardomattiucci

@tas

I'm noticing some flaws -- due to poor retraction. But these are flaws I can accept. The important thing is to print.
Maybe I'll increase to 0.7 mm for tomorrow's next print.

bernardomattiucci

Unfortunately, the printing has stalled again, at about 87 percent.
There is one thing to be said, however: I am printing in too cold an environment. Although my printer is closed, the printing chamber today never got above 18°C (I have no heating here in the attic). And I can't afford to keep the 1200Watt heated top on for 8 hours!!!!

Will I have to wait a few months?

tas

@bernardomattiucci
When I use higher temp materials I add insulating panels to the sides of my printer. But 18C is pretty cool. You probably want to add an insulated cover too.

Nothing expensive. I just use foamcore boards cut to size.

There was an issue with cracked drive gears or rusting on the Hemera a long time ago. Might be worth having a peek to see if that could be causing your intermittent retraction issues.

Check this link for more details:
https://e3d-online.com/blogs/news/hemera-issues-clarification-and-update

engikeneer

@bernardomattiucci I think you need to read up on heat creep in filament as it sounds like that is your issue.

Basically, over time heat creeps up the filament in the extruder. When the filament gets warm, it expands a little. If it expands too much, or even worse melts in the heatbreak, it can cause friction in the heatbreak and so cause a blockage.

In normal printing, you are constantly pushing fresh filament through, so no big issue. When you retract, you pull warm/hot filament back up and so it gets worse. Lots of retraction and travel means lots of time not extruding fresh plastic so it builds up more heat and is more likely to cause a blockage. Cheaper filaments may be more susceptible to this, or are just weaker hence the powerful hemera just strips it when things start getting stuck.

I would check your cooling setup on the hemera. Are you using their standard fan? Is there enough room for airflow around the heatsink? Have you set the motor to the correct current? Is the hotend assembled correctly, with suitable thermal paste, clearance to the heaterblock etc. Have you got a silicone sock over the heaterblock?